#ifndef _TextureManager_H__
#define _TextureManager_H__


#include "U2PreRequest.h"
#include "U2ResourceManager.h"
#include "U2Texture.h"
#include "U2Singleton.h"


U2EG_NAMESPACE_BEGIN


/** Class for loading & managing textures.
    @remarks
        Note that this class is abstract - the particular
        RenderSystem that is in use at the time will create
        a concrete subclass of this. Note that the concrete
        class will be available via the abstract singleton
        obtained from TextureManager::getSingleton(), but
        you should not assume that it is available until you
        have a) initialised Ogre (after selecting a RenderSystem
        and calling initialise from the Root object), and b)
        created at least one window - this may be done at the
        same time as part a if you allow Ogre to autocreate one.
 */
class _U2Share U2TextureManager : public U2ResourceManager, public U2Singleton<U2TextureManager>
{
public:

    U2TextureManager(void);
    virtual ~U2TextureManager();

    /** Create a new texture, or retrieve an existing one with the same
        name if it already exists.
        @param
            texType The type of texture to load/create, defaults to normal 2D textures
        @param
            numMipmaps The number of pre-filtered mipmaps to generate. If left to MIP_DEFAULT then
            the TextureManager's default number of mipmaps will be used (see setDefaultNumMipmaps())
            If set to MIP_UNLIMITED mipmaps will be generated until the lowest possible
            level, 1x1x1.
        @param
            gamma The gamma adjustment factor to apply to this texture (brightening/darkening)
        @param 
            isAlpha Only applicable to greyscale images. If true, specifies that
            the image should be loaded into an alpha texture rather than a
            single channel colour texture - useful for fixed-function systems.
        @param 
            desiredFormat The format you would like to have used instead of
            the format being based on the contents of the texture
		@param hwGammaCorrection Pass 'true' to enable hardware gamma correction
			(sRGB) on this texture. The hardware will convert from gamma space
			to linear space when reading from this texture. Only applicable for 
			8-bits per channel textures, will be ignored for other types. Has the advantage
			over pre-applied gamma that the texture precision is maintained.
        @see U2ResourceManager::createOrRetrieve
    */
    virtual ResourceCreateOrRetrieveResult createOrRetrieve(
        const U2String &name, const U2String& group, bool isManual = false,
        U2ManualResourceLoader* loader = 0, const NameValuePairList* createParams = 0,
        TextureType texType = TEX_TYPE_2D, int numMipmaps = MIP_DEFAULT, 
        u2real gamma = 1.0f, bool isAlpha = false,
        PixelFormat desiredFormat = PF_UNKNOWN, bool hwGammaCorrection = false);

    /** Prepares to loads a texture from a file.
        @param
            name The file to load, or a U2String identifier in some cases
        @param
            group The name of the resource group to assign the texture to
        @param
            texType The type of texture to load/create, defaults to normal 2D textures
        @param
            numMipmaps The number of pre-filtered mipmaps to generate. If left to MIP_DEFAULT then
            the TextureManager's default number of mipmaps will be used (see setDefaultNumMipmaps())
            If set to MIP_UNLIMITED mipmaps will be generated until the lowest possible
            level, 1x1x1.
        @param
            gamma The gamma adjustment factor to apply to this texture (brightening/darkening)
        @param 
            isAlpha Only applicable to greyscale images. If true, specifies that
            the image should be loaded into an alpha texture rather than a
            single channel colour texture - useful for fixed-function systems.
        @param 
            desiredFormat The format you would like to have used instead of
            the format being based on the contents of the texture
		@param hwGammaCorrection Pass 'true' to enable hardware gamma correction
			(sRGB) on this texture. The hardware will convert from gamma space
			to linear space when reading from this texture. Only applicable for 
			8-bits per channel textures, will be ignored for other types. Has the advantage
			over pre-applied gamma that the texture precision is maintained.
    */
    virtual U2TexturePtr prepare( 
        const U2String& name, const U2String& group, 
        TextureType texType = TEX_TYPE_2D, int numMipmaps = MIP_DEFAULT, 
        u2real gamma = 1.0f, bool isAlpha = false,
        PixelFormat desiredFormat = PF_UNKNOWN, bool hwGammaCorrection = false);

    /** Loads a texture from a file.
        @param
            name The file to load, or a U2String identifier in some cases
        @param
            group The name of the resource group to assign the texture to
        @param
            texType The type of texture to load/create, defaults to normal 2D textures
        @param
            numMipmaps The number of pre-filtered mipmaps to generate. If left to MIP_DEFAULT then
            the TextureManager's default number of mipmaps will be used (see setDefaultNumMipmaps())
			If set to MIP_UNLIMITED mipmaps will be generated until the lowest possible
			level, 1x1x1.
        @param
            gamma The gamma adjustment factor to apply to this texture (brightening/darkening)
				during loading
		@param 
			isAlpha Only applicable to greyscale images. If true, specifies that
			the image should be loaded into an alpha texture rather than a
			single channel colour texture - useful for fixed-function systems.
		@param 
			desiredFormat The format you would like to have used instead of
			the format being based on the contents of the texture. Pass PF_UNKNOWN
			to default.
		@param hwGammaCorrection Pass 'true' to enable hardware gamma correction
			(sRGB) on this texture. The hardware will convert from gamma space
			to linear space when reading from this texture. Only applicable for 
			8-bits per channel textures, will be ignored for other types. Has the advantage
			over pre-applied gamma that the texture precision is maintained.
    */
    virtual U2TexturePtr load( 
        const U2String& name, const U2String& group, 
        TextureType texType = TEX_TYPE_2D, int numMipmaps = MIP_DEFAULT, 
        u2real gamma = 1.0f, bool isAlpha = false,
        PixelFormat desiredFormat = PF_UNKNOWN, 
		bool hwGammaCorrection = false);

    /** Loads a texture from an U2Image object.
        @note
            The texture will create as manual texture without loader.
        @param
            name The name to give the resulting texture
        @param
            group The name of the resource group to assign the texture to
        @param
            img The U2Image object which contains the data to load
        @param
            texType The type of texture to load/create, defaults to normal 2D textures
        @param
            numMipmaps The number of pre-filtered mipmaps to generate. If left to MIP_DEFAULT then
            the TextureManager's default number of mipmaps will be used (see setDefaultNumMipmaps())
			If set to MIP_UNLIMITED mipmaps will be generated until the lowest possible
			level, 1x1x1.
        @param
            gamma The gamma adjustment factor to apply to this texture (brightening/darkening)
		@param 
			isAlpha Only applicable to greyscale images. If true, specifies that
			the image should be loaded into an alpha texture rather than a
			single channel colour texture - useful for fixed-function systems.
		@param 
			desiredFormat The format you would like to have used instead of
			the format being based on the contents of the texture
		@param hwGammaCorrection Pass 'true' to enable hardware gamma correction
			(sRGB) on this texture. The hardware will convert from gamma space
			to linear space when reading from this texture. Only applicable for 
			8-bits per channel textures, will be ignored for other types. Has the advantage
			over pre-applied gamma that the texture precision is maintained.
    */
    virtual U2TexturePtr loadImage( 
        const U2String &name, const U2String& group, const U2Image &img, 
        TextureType texType = TEX_TYPE_2D,
        int iNumMipmaps = MIP_DEFAULT, u2real gamma = 1.0f, bool isAlpha = false,
        PixelFormat desiredFormat = PF_UNKNOWN, bool hwGammaCorrection = false);
		
    /** Loads a texture from a raw data stream.
        @note
            The texture will create as manual texture without loader.
        @param
            name The name to give the resulting texture
        @param
            group The name of the resource group to assign the texture to
        @param
            stream Incoming data stream
        @param
            width, height The dimensions of the texture
        @param
            format The format of the data being passed in; the manager reserves
            the right to create a different format for the texture if the 
            original format is not available in this context.
        @param
            texType The type of texture to load/create, defaults to normal 2D textures
        @param
            numMipmaps The number of pre-filtered mipmaps to generate. If left to MIP_DEFAULT then
            the TextureManager's default number of mipmaps will be used (see setDefaultNumMipmaps())
			If set to MIP_UNLIMITED mipmaps will be generated until the lowest possible
			level, 1x1x1.
        @param
            gamma The gamma adjustment factor to apply to this texture (brightening/darkening)
			 while loading
		 @param hwGammaCorrection Pass 'true' to enable hardware gamma correction
			 (sRGB) on this texture. The hardware will convert from gamma space
			 to linear space when reading from this texture. Only applicable for 
			 8-bits per channel textures, will be ignored for other types. Has the advantage
			 over pre-applied gamma that the texture precision is maintained.

    */
    virtual U2TexturePtr loadRawData(const U2String &name, const U2String& group,
        U2DataStreamPtr& stream, u2ushort uWidth, u2ushort uHeight, 
        PixelFormat format, TextureType texType = TEX_TYPE_2D, 
        int iNumMipmaps = MIP_DEFAULT, u2real gamma = 1.0f, bool hwGammaCorrection = false);

	/** Create a manual texture with specified width, height and depth (not loaded from a file).
        @param
            name The name to give the resulting texture
        @param
            group The name of the resource group to assign the texture to
        @param
            texType The type of texture to load/create, defaults to normal 2D textures
        @param
            width, height, depth The dimensions of the texture
        @param
            numMipmaps The number of pre-filtered mipmaps to generate. If left to MIP_DEFAULT then
            the TextureManager's default number of mipmaps will be used (see setDefaultNumMipmaps())
			If set to MIP_UNLIMITED mipmaps will be generated until the lowest possible
			level, 1x1x1.
        @param
            format The internal format you wish to request; the manager reserves
            the right to create a different format if the one you select is
            not available in this context.
		@param 
			usage The kind of usage this texture is intended for. It 
			is a combination of TU_STATIC, TU_DYNAMIC, TU_WRITE_ONLY, 
			TU_AUTOMIPMAP and TU_RENDERTARGET (see TextureUsage enum). You are
        	strongly advised to use HBU_STATIC_WRITE_ONLY wherever possible, if you need to 
        	update regularly, consider HBU_DYNAMIC_WRITE_ONLY.
        @param
            loader If you intend the contents of the manual texture to be 
            regularly updated, to the extent that you don't need to recover 
            the contents if the texture content is lost somehow, you can leave
            this parameter as 0. However, if you intend to populate the
            texture only once, then you should implement U2ManualResourceLoader
            and pass a pointer to it in this parameter; this means that if the
            manual texture ever needs to be reloaded, the U2ManualResourceLoader
            will be called to do it.
		@param hwGammaCorrection Pass 'true' to enable hardware gamma correction
			(sRGB) on this texture. The hardware will convert from gamma space
			to linear space when reading from this texture. Only applicable for 
			8-bits per channel textures, will be ignored for other types. Has the advantage
			over pre-applied gamma that the texture precision is maintained.
		@param fsaa The level of multisampling to use if this is a render target. Ignored
			if usage does not include TU_RENDERTARGET or if the device does
			not support it.
    */
    virtual U2TexturePtr createManual(const U2String & name, const U2String& group,
        TextureType texType, u2uint width, u2uint height, u2uint depth, 
		int num_mips, PixelFormat format, int usage = TU_DEFAULT, U2ManualResourceLoader* loader = 0,
		bool hwGammaCorrection = false, u2uint fsaa = 0, const U2String& fsaaHint = U2StringUtil::BLANK);
		
    /** Create a manual texture with a depth of 1 (not loaded from a file).
        @param
            name The name to give the resulting texture
        @param
            group The name of the resource group to assign the texture to
        @param
            texType The type of texture to load/create, defaults to normal 2D textures
        @param
            width, height The dimensions of the texture
        @param
            numMipmaps The number of pre-filtered mipmaps to generate. If left to MIP_DEFAULT then
            the TextureManager's default number of mipmaps will be used (see setDefaultNumMipmaps()).
			If set to MIP_UNLIMITED mipmaps will be generated until the lowest possible
			level, 1x1x1.
        @param
            format The internal format you wish to request; the manager reserves
            the right to create a different format if the one you select is
            not available in this context.
		@param 
			usage The kind of usage this texture is intended for. It 
			is a combination of TU_STATIC, TU_DYNAMIC, TU_WRITE_ONLY, 
			TU_AUTOMIPMAP and TU_RENDERTARGET (see TextureUsage enum). You are
        	strongly advised to use HBU_STATIC_WRITE_ONLY wherever possible, if you need to 
        	update regularly, consider HBU_DYNAMIC_WRITE_ONLY.
        @param
            loader If you intend the contents of the manual texture to be 
            regularly updated, to the extent that you don't need to recover 
            the contents if the texture content is lost somehow, you can leave
            this parameter as 0. However, if you intend to populate the
            texture only once, then you should implement U2ManualResourceLoader
            and pass a pointer to it in this parameter; this means that if the
            manual texture ever needs to be reloaded, the U2ManualResourceLoader
            will be called to do it.
		 @param hwGammaCorrection Pass 'true' to enable hardware gamma correction
			 (sRGB) on this texture. The hardware will convert from gamma space
			 to linear space when reading from this texture. Only applicable for 
			 8-bits per channel textures, will be ignored for other types. Has the advantage
			 over pre-applied gamma that the texture precision is maintained.
		@param fsaa The level of multisampling to use if this is a render target. Ignored
			if usage does not include TU_RENDERTARGET or if the device does
			not support it.
    */
    U2TexturePtr createManual(const U2String & name, const U2String& group,
        TextureType texType, u2uint width, u2uint height, int num_mips,
        PixelFormat format, int usage = TU_DEFAULT, U2ManualResourceLoader* loader = 0,
		bool hwGammaCorrection = false, u2uint fsaa = 0, const U2String& fsaaHint = U2StringUtil::BLANK)
	{
		return createManual(name, group, texType, width, height, 1, 
			num_mips, format, usage, loader, hwGammaCorrection, fsaa, fsaaHint);
	}

    /** Sets preferred bit depth for integer pixel format textures.
    @param
        bits Number of bits. Available values: 0, 16 and 32, where 0 (the default) means keep
        original format as it is. This value is number of bits for the pixel.
    @param
        reloadTextures If true (the default), will reloading all reloadable textures.
    */
    virtual void setPreferredIntegerBitDepth(u2ushort bits, bool reloadTextures = true);

    /** gets preferred bit depth for integer pixel format textures.
    */
    virtual u2ushort getPreferredIntegerBitDepth(void) const;

    /** Sets preferred bit depth for float pixel format textures.
    @param
        bits Number of bits. Available values: 0, 16 and 32, where 0 (the default) means keep
        original format as it is. This value is number of bits for a channel of the pixel.
    @param
        reloadTextures If true (the default), will reloading all reloadable textures.
    */
    virtual void setPreferredFloatBitDepth(u2ushort bits, bool reloadTextures = true);

    /** gets preferred bit depth for float pixel format textures.
    */
    virtual u2ushort getPreferredFloatBitDepth(void) const;

    /** Sets preferred bit depth for integer and float pixel format.
    @param
        integerBits Number of bits. Available values: 0, 16 and 32, where 0 (the default) means keep
        original format as it is. This value is number of bits for the pixel.
    @param
        floatBits Number of bits. Available values: 0, 16 and 32, where 0 (the default) means keep
        original format as it is. This value is number of bits for a channel of the pixel.
    @param
        reloadTextures If true (the default), will reloading all reloadable textures.
    */
    virtual void setPreferredBitDepths(u2ushort integerBits, u2ushort floatBits, bool reloadTextures = true);

	/** Returns whether this render system can natively support the precise texture 
		format requested with the given usage options.
	@remarks
		You can still create textures with this format even if this method returns
		false; the texture format will just be altered to one which the device does
		support.
	@note
		Sometimes the device may just slightly change the format, such as reordering the 
		channels or packing the channels differently, without it making and qualitative 
		differences to the texture. If you want to just detect whether the quality of a
		given texture will be reduced, use isEquivalentFormatSupport instead.
	@param format The pixel format requested
	@param usage The kind of usage this texture is intended for, a combination of 
		the TextureUsage flags.
	@returns true if the format is natively supported, false if a fallback would be used.
	*/
	virtual bool isFormatSupported(TextureType ttype, PixelFormat format, int usage);

	/** Returns whether this render system can support the texture format requested
		with the given usage options, or another format with no quality reduction.
	*/
	virtual bool isEquivalentFormatSupported(TextureType ttype, PixelFormat format, int usage);

	/** Gets the format which will be natively used for a requested format given the
		constraints of the current device.
	*/
	virtual PixelFormat getNativeFormat(TextureType ttype, PixelFormat format, int usage) = 0;

    /** Returns whether this render system has hardware filtering supported for the
        texture format requested with the given usage options.
    @remarks
        Not all texture format are supports filtering by the hardware, i.e. some
        cards support floating point format, but it doesn't supports filtering on
        the floating point texture at all, or only a subset floating point formats
        have flitering supported.
    @par
        In the case you want to write shader to work with floating point texture, and
        you want to produce better visual quality, it's necessary to flitering the
        texture manually in shader (potential requires four or more texture fetch
        instructions, plus several arithmetic instructions) if filtering doesn't
        supported by hardware. But in case on the hardware that supports floating
        point filtering natively, it had better to adopt this capability for
        performance (because only one texture fetch instruction are required) and
        doesn't loss visual quality.
    @par
        This method allow you queries hardware texture filtering capability to deciding
        which verion of the shader to be used. Note it's up to you to write multi-version
        shaders for support various hardware, internal engine can't do that for you
        automatically.
    @note
        Under GL, texture filtering are always supported by driver, but if it's not
        supported by hardware natively, software simulation will be used, and you
        will end up with very slow speed (less than 0.1 fps for example). To slove
        this performance problem, you must disable filtering manually (by use
        <b>filtering none</b> in the material script's texture_unit section, or
        call TextureUnitState::setTextureFiltering with TFO_NONE if populate
        material in code).
	@param ttype The texture type requested
	@param format The pixel format requested
	@param usage The kind of usage this texture is intended for, a combination of 
		the TextureUsage flags.
    @param preciseFormatOnly Whether precise or fallback format mode is used to detecting.
        In case the pixel format doesn't supported by device, false will be returned
        if in precise mode, and natively used pixel format will be actually use to
        check if in fallback mode.
	@returns true if the texture filtering is supported.
    */
    virtual bool isHardwareFilteringSupported(TextureType ttype, PixelFormat format, int usage,
        bool preciseFormatOnly = false) = 0;

    /** Sets the default number of mipmaps to be used for loaded textures, for when textures are
        loaded automatically (e.g. by Material class) or when 'load' is called with the default
        parameters by the application.
		If set to MIP_UNLIMITED mipmaps will be generated until the lowest possible
			level, 1x1x1.
        @note
            The default value is 0.
    */
    virtual void setDefaultNumMipmaps(size_t num);

    /** Gets the default number of mipmaps to be used for loaded textures.
    */
    virtual size_t getDefaultNumMipmaps()
    {
        return mDefaultNumMipmaps;
    }

    /** Override standard U2Singleton retrieval.
    @remarks
    Why do we do this? Well, it's because the U2Singleton
    implementation is in a .h file, which means it gets compiled
    into anybody who includes it. This is needed for the
    U2Singleton template to work, but we actually only want it
    compiled into the implementation of the class based on the
    U2Singleton, not all of them. If we don't change this, we get
    link errors when trying to use the U2Singleton-based class from
    an outside dll.
    @par
    This method just delegates to the template version anyway,
    but the implementation stays in this single compilation unit,
    preventing link errors.
    */
    static U2TextureManager& getSingleton(void);
    /** Override standard U2Singleton retrieval.
    @remarks
    Why do we do this? Well, it's because the U2Singleton
    implementation is in a .h file, which means it gets compiled
    into anybody who includes it. This is needed for the
    U2Singleton template to work, but we actually only want it
    compiled into the implementation of the class based on the
    U2Singleton, not all of them. If we don't change this, we get
    link errors when trying to use the U2Singleton-based class from
    an outside dll.
    @par
    This method just delegates to the template version anyway,
    but the implementation stays in this single compilation unit,
    preventing link errors.
    */
    static U2TextureManager* getSingletonPtr(void);

protected:

    u2ushort mPreferredIntegerBitDepth;
    u2ushort mPreferredFloatBitDepth;
    size_t mDefaultNumMipmaps;
};


U2EG_NAMESPACE_END


#endif
